2G P0340 code, backfire and ignition miss

[Turbo Mike]

Hello,

New member. Just bought a 98 GST. Been doing a bunch of searching on the interwebs for an answer to my problem with no luck. Has an issue when running for about 20 minutes. Engine develops a misfire, loss of power, backfires out the exhaust, won't rev, tach drops rpm. I keep getting code P0340. I replaced the cam position sensor and the problem still exists. When the car sits and cools down for about 20 minutes it's fine again. I checked voltage at the cam sensor and everything looks normal. I pulled the cam sensor housing to check for any abnormalities. I installed a Walbro 255lph fuel pump just because I had one. I replaced the spark plugs with NGK BPR7ES gapped to .024, did a compression test, everything looks good. Plug wires are brand new NGK.
As far as I know the car is stock except for 3" turbo back exhaust, upgraded intercooler, and maybe an upgraded turbo? (says TD05H on it).
I am stumped. Any advise or help would be greatly appreciated.

Thanks in advance.

 

[spyderdrifter]

A tdo5h would be an upgrade for your car. Here's a little help..

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[Turbo Mike]

Thanks spyderdrifter.
I tried another power transistor but that didn't fix it. Still searching.

 

[Turbo Mike]

Problem solved !

I had replaced the ignition coils with aftermarket units. Apparently they were faulty. I purchased a used pair and it solved the problem.